1. Field of the Invention
The present invention relates to a ceramic member for a living body which can be used as an extraction cavity filling material and a method of manufacturing the same.
2. Description of the Related Art
Recently, a ceramic member for a living body using a ceramic material having affinity with a living body has been manufactured. An example of the ceramic member for a living body is a filling material for a bone deficient portion. Examples of such a ceramic member are a dense material, a porous material, and a granule. A member for a living body consisting of a dense material has high strength and is resistant to infection since bacteria hardly enter into the member. A member for a living body consisting of a porous material or a granule can easily provide a good bonding state with a bone since it allows easy formation of a bone tissue in pores or gap portions of the member.
Therefore, ceramic members for a living body having the above properties are conventionally used as, e.g., an extraction cavity filling material. A ceramic member for a living body will be described below by taking an extraction cavity filling material as an example. The extraction cavity filling material is a filling material for preventing bone absorption and alveolar ridge lowering in an extraction cavity produced after tooth extraction. An extraction cavity filling material consisting of a ceramic material having affinity with a living body generally has a structure in which the dense material or a single-crystal material is used in a core portion and a porous material is coated on the surface of the core portion. With such a structure, the strength as a root and the affinity with a bone tissue are obtained.
An example of such an extraction cavity filling material is proposed in Published Unexamined Japanese Patent Application No. 61-50558. This extraction cavity filling material is obtained by molding a calcium phosphate compound consisting of a porous or dense material into a truncated cone or a circular pillar. Alveolar ridge lowering after tooth extraction can be prevented by transplanting an extraction cavity filling material having such a shape in an extraction cavity.
Ceramic members for a living body obtained by conventional manufacturing methods, however, are sometimes not firmly bonded to a bone tissue or cause infection with high possibility. For example, when a porous material is used as an extraction cavity filling material, bacteria easily enter into small pores formed in the surface of the material. Therefore, a gum portion which is in contact with the material is infected.
When a granule is used as an extraction cavity filling material, the material may be dislodged by an internal pressure or the like if another tooth is lost to lower an alveolar ridge.
In addition, when a dense material is used as an extraction cavity filling material, the material is not firmly bonded to a bone material since the bone tissue is not formed in the dense material.
Furthermore, in order to form an artificial root in an extraction portion, a root post must be transplanted in an extraction cavity filling material. Since, however, conventional extraction cavity filling materials do not have a function as an artificial root receiving member, an artificial root cannot be formed.